This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The objective of this study is to define the consequences of naturally-occurring age-related hearing deficits on the structure and function of the central auditory system. These results will be used to develop more effective hearing-assist devices (hearing aids) for the 70 million Americans that currently suffer from age-related hearing deficits.